In the field of metal packaging, easy open ends for metal cans are well known. Typically, an easy open can end takes the form of a metal panel including a score line defining an opening area on the can end. A tab is provided on the can end, with lifting of the tab by a consumer initiating fracture of the score line and subsequent pulling on the tab resulting in opening of the can end about the opening area. Historically, the opening of such easy open ends was made difficult by limited clearance between the tab and the can end, thereby making it hard for a consumer to engage the tab with their fingers. WO 03/104092 A (MAEIL DAIRY INDUSTRY CO., LTD) 18.12.2003 (subsequently assigned to CROWN Packaging Technology, Inc for US and EP designations) provided a solution to this problem, with the can end including a collapsible protrusion located beneath the tab. The collapsible protrusion of WO 03/104092 A is deformable from an upward position to a downward position. In the upward position, the can ends are readily stackable for transportation (i.e. before being attached to a container), but provide little or no clearance between the can end and the tab. When deformed into the downward position (typically after being attached to a can body), the protrusion then provides clearance between the tab and can end to enable a user to engage their fingers with the tab and open the can.
However, it has been found that during subsequent handling of containers incorporating can ends of the type described in WO 03/104092 A (i.e. after filling and any retort processing), there can be a tendency for the protrusion to “pop up” back into its upward position, thereby hindering tab access for a consumer. The cause of the popping-up could be, for example, impacting of the container against other containers or being dropped onto the floor. Similarly, the protrusion could pop back up when transported at high altitudes, where the lower atmospheric pressure would result in a lower pressure differential between the inside and outside of the container.
Consequently, there is a need for an improved easy open can end providing increased assurance of maintaining tab access for a consumer.